1. Technical Field
The present invention relates to a flat burner for use in a combustion apparatus such as a heat source apparatus for hot water supply and the like.
2. Background Art
Generally, in a heat source apparatus for hot water supply, a plurality of flat burners each having a rectangular flame port portion at an upper end thereof is disposed in parallel with one another in a combustion box which forcibly supplies combustion air by means of a combustion fan.
Conventionally, this kind of flat burner with a flame port portion has a burner main body which is made up of a pair of side plates lying opposite to each other in a lateral direction where a longitudinal direction of the flame port portion is defined as a back-and-forth direction and a width direction of the flame port portion is defined as a lateral direction. The burner main body has formed therein a mixing tube portion at a lower part of the burner main body, and a distribution chamber portion which introduces a fuel-air mixture from the mixing tube portion into the flame port portion. The flame port portion has mounted therein a straightening member with a plurality of straightening plates laterally disposed in parallel with one another (see, for example, JP-A-1995-91620). The straightening member has contact portions in which the straightening plates are brought into contact with one another at a plurality of longitudinal positions to thereby longitudinally segregate the flame port passages that are defined by each of the straightening plates.
By the way, in order to downsize the heat source apparatus, it is sometimes required that the vertical dimensions of the distribution chamber portion of the flat burner be shortened. However, should the vertical dimensions of the distribution chamber portion be shortened, the inlet direction of flow of the fuel-air mixture from the distribution chamber portion into the flame port portion at the front part and the rear part of the flat burner will largely be inclined longitudinally relative to the vertical direction. Here, in the laterally center-side of the flame port passage, the flow velocity of the fuel-air mixture becomes larger and the flame formed over the flame port passage becomes large. Then, if the inlet direction of flow of the fuel-air mixture into the flame port passage in the laterally center-side of the front part and the rear part of the burner becomes largely inclined longitudinally, the large flame formed in this flame port portion over the flame port passage will be inclined longitudinally. As a result, the front surface and the rear surface of the combustion box will be intensely heated, thereby giving rise to a heat loss of the combustion box.